In electronic devices with integrated circuits (ICs), the ICs are typically mounted onto circuit boards. In order to electrically couple connections between the circuit board and the IC, the IC is typically “packaged.” The IC packaging usually provides a small encasement for physically protecting the IC and provides contact pads for coupling to the circuit board. In some applications, the packaged IC may be coupled to the circuit board via solder bumps.
One approach to IC packaging comprises a quad-flat no-leads (QFN) package. The QFN package may provide some advantages, such as reduced lead inductance, a near chip scale footprint, thin profile, and low weight. Also, the QFN package typically includes perimeter I/O pads to ease circuit board trace routing, and the exposed copper die-pad technology offers enhanced thermal and electrical performance. QFN packaging may be well suited for applications where size, weight, and thermal and electrical performance are important.
Referring initially to FIG. 1, a typical ball grid array (BGA) electronic device 200 is now described. The electronic device 200 includes a heat sink layer 201, a pair of stiffeners 203a-203b, and an adhesive layer 202a, 202c between the stiffeners and the heat sink layer. The electronic device 200 includes a circuit board layer 205 having electrically conductive traces 208 therein, another adhesive layer 204a-204b between the circuit board layer and the stiffeners 203a-203b, and a plurality of ball contacts 207a-207l carried by the circuit board layer. The electronic device 200 includes an IC 206, a plurality of ball contacts 209a-209j coupling the IC to the circuit board layer 205, an adhesive layer 202b between the heat sink layer 201 and the IC, and an under fill material 210 around the IC and surrounding the plurality of ball contacts.